NEVER USE OIL AS A LUBE IF YOU EVER INTEND TO USE LATEX CONDOMS
Oil destroys latex in a very VERY short time - blow a condom up like a baloon and spritz it with baby oil - it will generally burst in a few minutes.
It's not possible to wash all traces of oil out of the vagina (the anus does get flushed out with fecal transit, but it still takes ages - you've not indicated if you are male or female, or the gender of your partner, so forgive my not being clear), so you have a very high chance that you will suffer contraceptive failure.
Olive Oil can feed and protect bacteria, and therefore can lead to BV etc.
Olive oil's not cheap, use the money to buy a condom friendly lube.
